${4 \div 0.1 = {?}}$
Solution: $ {4 \div 0.1 = 4 \div \dfrac{1}{10}} $ Dividing by a fraction is the same as multiplying by the reciprocal of the fraction. $ {4 \div \dfrac{1}{10} = 4 \times \dfrac{10}{1}} $ $ {\phantom{4 \div \dfrac{1}{10}} = 40} $